Air gun or rifle plunger



Jan. 12

' 4 1,569,030 M. R. RANDALL AIR GUN OR RIFLE PLUNGER Filed March 18 1924 Patented Jan. 12, 1926.

UNITED STATEfi MYRON R. RANDALL, 0F WAUPACA, WISCONSIN.

AIR GUN on RIFLE rnnnenn.

Application filed March 18, 1924.. Serial No. 700,142.

To all whom it may concern:

Be it known that I, MYRoN R. RANDALL, a citizen of the United States, residing at Waupaca, in the county of Waupaca. and State of Wisconsin, have invented certain new and useful Improvements in Air Gun or Rifle Plungers, of which the following is a specification.

My invention relates to an air gun or rifle plunger.

This application is a. continuation in part of my application forair gun plunger or piston, 680,133, filed December 12th, 1923, which last named application is a division of my copending application for air gun or rifle, filed February 26th, 1924, Serial No. 621,401.

An important object of the invention is to provide an air gun or rifle plunger, which is capable of obtaining the maximum comprcssion, combined with long wear, and the minimum friction, whereby theplunger may have the maximum velocity.

A further object of the invention is to provide a plunger of the above mentioned character which will operate with the maximum compression, for themaximum length of time, with the least lubrication.

A further object of the invention is to provide a plun er of the above mentioned character, so constructed that the several packing rings may be properly applied thereto quickly and easil Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification, and in which like numerals are employed to designate like parts throughout the same,

Figure l is a. side elevation of a plunger embodying my invention, the air chamber and associated elements being shown in section, V

Figure 2 is a central. longitudinal sectional View through the same,

Figure 3 is a perspective view of the elements constituting the packing,

If igure 4 is a side elevation of a piston ring, illustrating the customary manner of machining the same, and,

- Figure 5 is a-similar view of one of the rings upon my air gun or rifle plunger,

illustrating the manner of machining the same.

The efficiency of an air gun or rifle, part-icularly of the high power type, is dependent principally upon the efficiency of the plunger. This feature, hasflong been recognized by the workers in the air gun art, and the patents issued in that art, show clearly that numerous attempts have been made to increase the efliciency of the mum compression, which can be obtained by its use, but there is a decided disadvantage, which is the creation of excessive friction. This friction cuts down the velocity of the plunger, in turn impairing the efficiency of the gun. Further, this soft packing, readily distorts or expands, under the hammering action of the plunger, whereby the friction increases rapidly. As a result of the use of the soft packing, excessive friction is always present in an air gun or rifle, and this requires frequent lubrication, in order that the gun may be shot with satisfactory results. In the high powered English air gun, a leather packing is employed upon the plunger, and it is necessary to lubricate the gun frequently. I have found that after this gun has been shot for ten times, without lubrication, that its efficiency will decrease materially. Further, the soft packing wears quickly, and hence will lose compression in use.

As above stated, as far as I am aware, it is the settled practice to employ this soft packing upon the plunger of an air gun or rifle, and I do not believe that anyone has heretofore successfully used. a hard radially resilient plit packing ring, such as a cast iron packing ring, or a hard fibre packing ring, upon the plunger of an air gun.

In my experiments in perfecting my air gun, my attention 1 was directed to the marked inefficiency of the plunger of the air gun and I attempted to overcome the same. 7

My first experiments were with the use of the soft packing, such as leather, and in this respect I followed the teachings of the prior air gun art. I became convinced that a whollyv satisfactory packing could not be obtained by the use of soft'paclring.

I then turned to the use of a cast iron packing ring, which wassplit, andv radially resilient. I placed this ring upon the plunger of my air gun, and tested the same, and

found that the results werewholly unsatisfactory. The ring did not produce sufficient compression, and the fr ction was 4 excessive, so that the'velocity of the plunger was the annular blank from which the ring is formed, and cut out a portion of the metal from such blank. This cut may be fivesixteeiiths ofan inch, while thismay vary, increasing. with the increased diameter of the ring; The split ring is then compressed or drawn together so that the cut ends contact, and the compressed ring. is then clamped upon an arbor. The periphery of the compressed ring is then machined down, andinfollowing the settled practice in the internal combustion engine art, I machined the'cast iron ring down to a slight oversize, about one one-thousandth of an inch oversize in diameter. with respect to'the diameter of the'bore of the air chamber of-the air gun; When the ring was taken off of the arbor, it was allowed to expand, and following the practice of the internal 'combustion engine art, the ends of thelring. were.

filed down "sufficiently whereby the ring could be compressed 'sufliciently to enter the bore of the air chamber. b

In the experiments with my first ring, I machined the same to a slight oversize, as above stated, as is the settled practice in the internal "combustion, engine art, and found that'this wouldiiot produce satisfactory results. The ring thus obtained. produced excessive friction and insufiicient compression, I found that the ring tended to contact at its free ends and at a point diametrically opposite such, freeends.

. Havingthus met with'failure' in attempting to usethe cast iron netal packing ring,

in accordance with the teachings of the prior internal combustion engine art, I became very much discouraged and had al- .most'concluded that such a'r'ing could not be succ'essivelyemploye'd forthe purpose sandths of an inch. The blank thus cut or split was compressed so that its end contacted and the compressed blank was clamped to the arbor, of the lathe, and the periphery; of the ring machined down very accurately, but-slightly below thev diameter of the bore of the air ch'ambeiu' This machining was carr ed out to one four-thousandths-of an 1I1Cl1; 111, d ameter of the ring with respect to the diameter of the bore of the air chamber. As a result of this accurate machining, below the diameter of the air chaii'iber, which is the reverse of the settled practice in the internal combustion engine art, all difiiculty was at once overcome, and

a plunger obtainedproducing highly satisfactory results. I obtain high compression with the least friction, with the inaximum velocity of the plunger. The ringcontacted substantially evenly throughout its area, with the wall of the air. chamber.

In'the drawings, wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral 5 designates the receiver of my air gun or.

rifle, as shown in my conending annlication Serial, No. 621,421, hereinbefore. referred to.;

Mounted. to reciprocate within this carrier is the air chamber 6, which is of a relatively small diameter, This air chamber is pro vided at its forward end, with a tubular socket 7, adapted to receive therein the re duced end or extension 8 of the barrel 9 of the rifle. Awhard fibre washer 10. is mounted within the forward end of the air chamber, to take the impact fromthe plunger, and liasan opening llv incommunication with the bore of the, barrel. Compressible packing 12 is confined. between the washer lOandthe forward end ofthe air chamber,

as shown. As the air chamber. is not claimed per se in the present application, it ,is thoughtthat no further description of the same isdeemed necessary.

The nuineral l3 lesignates a plunger-as a whole, which is used in my air gun or rifle,

flange 16, provided with annular grooves 17, carrying lubricating rings 18, which may be made of felt, or any othersuitable material. The body portion 14 is provided with a forwardly extending portion 19, which is diametrically reduced or contracted, and is adapted for the reception of the packing rings of the plunger. The contracted portion 19 is cylindrical and is integral with the body portion 14.

I have found that the packing rings, to be described, are of great importance, as I have been able to obtain the maximum compression, the least friction, the high veloc- 1ty of the plunger, and the minimum use of lubrication.

The numerals 20 and 21, designate rings or carriers, which are integral, that. is not split, and formed of metal. These rings or carriers'are L-shaped in cross section and are slipped upon the reduced portion 19 of the plunger, over the forward. end thereof. The carrier 20 supports the split packing ring 22, preferably formed of cast iron, while the carrier 21 supports the split packing ring 23, preferably formed of hard fibre, namely, hard vulcanized fibre, or other non-metallic material, possessing similar characteristics. It might be stated at this point that, by the use of the terms hard relatively non-con'ipressible material in the claims, I mean such a material having the characteristics of hard metal, such as cast iron, or hard vulcanized fibre, as distinguished from a packing which is relatively soft and compressible, and will distort under action, such as leather, raw hide, and other fibrous or cotton packing. Arranged forwardly of the carrier 20 is a solid or integral packing ring 24-, which is not split, and preferably formed of hard vulcanized fibre, although any other suitable non-metallic material, having like properties may be employed. The several rings are retained in place upon the reduced portion 19 of the plunger by means of a head or cap 25, secured to the reduced portion 19 by means of a screw 26 or the like. The precise construction of the plunger and its packing means are preferred, although changes may be resorted to.

I provide the solid non-split ring 24, formed of fibre, as the same constitutes a guide means for the plunger within the air chamber, and the fibre will slide within the air chamber with the least friction. I-

have also found that satisfactory results are obtainable by using the split ring 22 of cast iron and the split ring 23 of hard vulcanized fibre. The cast iron packing ring tends to produce better compression, but there is a tendency to develop friction, while the split fibre ring does not tend to produce quite as much compression, but less friction.

I have found that highly advantageous re-' sults are obtainable by employing the two split packing rings, one of cast iron and the other of fibre, and having their combined cross-sectional areas equal about to that of expand, and properly fit the inner wall of the air chamber. Further, the carriers, with the reduced portion or. extension of the plunger, enable these rings to he slipped into position, without radial expansion. If

a ring of the small diameter of these rings,

were attempted to be sprung in place upon the plunger, they would either break, or become permanently distorted.

Experiments which I have made, show that satisfactory results can be obtained by equipping the plunger of an air gun with a single split cast iron ring, and also that satisfactory results can be obtained by equipping, the plunger with a. single split vulcanized hard fibre ring. The difference in the use of the two rings, is slight, and I believe that there is a slight advantage in using the hard fibre ring. The hard fibre ring is produced in precisely the same manner as the metal ring, and is split, compressed, and then accurately machined to a diameter slightly below the lit of the diameter of the air chamber, to about one fourthousandth of an inch.

In Figure 4, I have illustrated a piston ring 27, as ordinarily employed in an internal combustion engine, and the ring is machined with a diameter slightly over the diameter of the bore of the cylinder, which cylinder diameter is indicated at 28. Figure 5 illustrates the manner of producing the rings for my air gun or rifle. The ring is indicated at 29, which ring may be either a split cast iron ring or a split hard vulcanized fibre ring. The ring is machined slightly below the diameter of the bore of the air chamber, and 30 designates the bore of the air chamber. As'I have heretofore stated, highly satisfactory results have been ob tained by machining the rings, for use in my air gun, to a diameter of one four-thousandth of an inch beneath the diameter of the bore of the air chamber. The rings must be machined thus accurately, and the machining must be below the diameter of the bore of the air chamber. This produces {ugh compression with the minimum fric- Experiments which I have conducted, show me that with the best of the common type of plungers in air guns, embodying the soft packing, it is necessary to oil the chamber about every twenty-five shots, to obtain a uniform velocity, at anywhere near the maximum, and it is frequently necessary to oil the air chamber, particularly in a high powered air ,gun, after the; gun- .is

plunger equipped With the hard rings, 1,

have t'ound that the gun will tire with uni form velocity for approximately atwo hundred shots or more, foreach-lubricatmn of the air chamber. I havefound that my gun develops unusual power, and willdrive a twenty-two bullet through aboard from three-fourths to seven-eighths of an inch thick, causing the bulletsto strike upon a hard metal plate and flatten out.

It is to be understood that the formiof' my invention herewith shown and described is to be taken asa preferred embodiment-of the same, and that various changes ln'tl16 shape, size. anduarrangement vlot parts may be resorted to, Without departing from the spirit of my inventiomor the scope of the subjoined claims.

Having thus described claim:

1. An air gun or rifle hard fibre ring mounted thereon to serve as guide means, a split resilient metallic my invention, I

packing ringcarried by the plunger at the plunger, a solid a rear of the solid ring,-and asplithard fibre fired: for tens shots. With mygun, having a packing; ring" carried :by'the plunger at the rear of the metallic ring. 25An i1=1-1'.-'QL1ll OI't'TfllG plunger, a split radially resilient metallic packingring'ca-F ried by the plunger, and a split radially resilient hard fibre packing-:rin-grcarried by the plunger. a

3); An air gun or r1fle-plunger, and aspllt' radially resilientpackingiringLcaPriedLby the plunger, said packing ring being-formed of a hard relatively non-compressible material, said packing ring being machined slightly below the.diameterptthebore ot the=air chamber.

4. An airgun or rifle plunger, and'asplit radially resilient" packing ring' carried-by" the plunger, said packing ring beingform'ed of a hard relatwely non-compress1ble material, said packing ring being machined slightly below the diameter of the bore of the air chamber, said split bei-ngfi'ne whereby the ring will producethe least friction by sliding contact with the air chamber.-

In testimony whereof I affix my signature.

' MYRON R1 RANDALL. 

